Electric plug and socket organization



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R. w. E. MOORE ELECTRIC PLUG AND SOCKET ORGANIZATION kmwx w Filed Nov. 25, 1933 Oct. 27, 1936.

w, m M m, m0 m H, m J x y zz/140m Oct. 27, 1936. R; w. E. MOORE ELECTRIC PLUG QID SOCKET ORGANIZATION Filed Nov. 25, 1935 4 Sheets-Sheet 3 q v lN vENT OR Jiagvk FI -E1100)? a" M. 7613' AT RNEYS Patented Oct. 27, 1936 UNITED STATES PATENT OFFICE This invention relates to an electric plug and socket organization which is particularly applicable to fuse plugs.

ELECTRIC PLUG AND SOCKET ORGANIZATION Ralph w. E. Moore, Pittsburgh, Pa., assignor to National Electric Products Corporation, Pittsburgh, Pa., a corporation of Delaware Application November 25, 1933, Serial No. 699,652

12 Claims. (Cl. 200-119) Fusing of electric circuits is widely accomsocket contacts.

5 plished by means of plug fuses which are screwed into electric sockets of conventional form. When a fuse burns out it is not uncommon for an unskilled and ill advised person to reestablish the circuit by inserting a coin or other conducting arfacturers.

er contact is advanced into engagement with the up as in bottom contact of the socket by the insertion of a special fuse.

Lighting companies are called upon to fuse bled fuse body.

sockets made by a wide variety of manufacturers may shown in w and these sockets vary considerably in the height of the bottom socket contact above the bottom of the socket. In some instances, the bottom socket contact is a screw head which projects quite a distance above the bottom of the socket, as shown in 36 he Schmidt patent, and as shown in Fig. 10 of the accompanying drawings. In other instances, the bottom contact may be close to the bottom of the socket as shown in Fig. 1 of the accompanying drawings. Thus, in order that an adapter of the type shown in the Schmidt patent may properly cooperate with the sockets made by various manufacturers, it is necessary that the movable contact of the adapter have a very large range of socketmovement.

This can be done, but introduces 40 manufacturing difficulties.

The present invention is in some respects an improvement upon the construction disclosed in the Schmidt patent, an object of the invention being to provide a circuit breaking adapter which 5 may be used with the various types of commersocketcial fuse sockets without providing for a long range of movement of the circuit breaking contact of the adapter.

.Another object of the invention is to provide a circuit breaking fuse plug adapter in which the circuit breaking contact of the adapter has the same range of movement regardless of the particular commercial socket into which it may be inserted.

Another object of the invention is to provide a lI-ll of Fig. 12.

circuit breaker adapter construction in which adequate clearance of the circuit breaking contacts is assured regardless of the arrangement of A further object of the invention is to provide an adapter which will properly cooperate with, and be retained in, the screw shell of the commercial fuse sockets made by the various manu- Other objects. of the invention are to improve the construction of fuse plugs and adapters from both manufacturing and operating standpoints.

Fig. l is an enlarged central vertical section showing a .fuse plug and adapter embodying the present invention, in place in a fuse socket.

Fig. 2 is an inverted sectional view, taken approximately on line 22 of Fig. 1.

Fig. 2 15 a fragmentary-detail section taken on the line 2 of Fig. 2, the parts being right side Fig. 3 is an enlarged plan view of an unassem- Fig. 5 is an enlarged elevation, partially in section. showing an unassembled adapter body.

Fig. 6 is an enlarged fragmentary central vertical section of an unassembled fuse cap.

Fig. 7 is a greatly enlarged fragmentary section taken on the line '|--'l of Fig. 6,.

Fig. 8 is a greatly enlarged fragmentary section taken on the line 8-8 of Fig. 4.

Fig. 9 is a greatly enlarged fragmentary section taken on the line 99 of Fig. 4.

Fig. 10 is an enlarged centralvertical section showing a modified form of fuse and adapter embodying the present invention, assembled in a Fig. 11 is an enlarged fragmentary vertical section showing a third specific form of fuse andadapter embodying the present invention.

Fig. 12 is an enlarged central vertical section showing a fourth specific form of fuse and adapter embodying the present invention, assembled in a Fig.- 13 is an inverted plan view of the adapter shown in Fig. 12, taken approximately on the line The socket l2 comprises an insulating base It (usually porcelain) which supports and surrounds Fig. 4 is an elevation of the unassembled fuse a sheet metal screw socket member l4 and a center or base contact 5. Suitable terminals are, of course, provided for making wiring connection to the socket shell I4 and the center contact i5, but these are not shown since they are standard fuse socket features which form no part of the present invention.

The adapter 20 will now be described, reference being had to Figs. 1, 2, and 5. The adapter is built about an adapter body 2| of molded insulating material which has upper and lower central recesses 22 and 23. The lower recess 23 is closed by an annular conical cap 24 of insulating material, which supports a metal center contact 25. A thread 26 is molded about the periphery of the adapter body; and making a tight screw fit therewith is a threaded sheet metal sleeve 2'! having an inwardly extending annular flange 28 which engages the cap 24. Thus, the sleeve 21 and the cap 24 are fixedly secured to the adapter body 2|. About the upper recess 22 there is an annular wall portion 38; and the outer face of the wall is provided with six vertical grooves 29. A centrally located threaded aperture 38 (Fig. 5) passes from the upper recess 22 to the lower recess 23; and into it there is screwed a metal circuit making and breaking plug 3 I. Within the lower recess 23 there is a spiral spring 32 (of suitable hairspring type) having its inner end passed diametrically through the bottom of plug 3|, and its outer end 33 secured against rotation by being inserted into any one of four slots 34 that lead oif from the side wall of recess 23. In assembly the spring is so tensioned that it rotatively biases plug 3| to normally keeping plug 3| out of engagement with contact 25. Secured to body 2| is a barb 35 which projects through adapter sleeve 21, to engage socket l4 and thereby prevent removal of the adapter from a socket into which it has been inserted,

The fuse plug is composed of a number of parts all of which are shown in Fig. 1 and some of which are shown in Figs. 3, 4, and 6. In Figs. 3 and 4 there is shown a single molded piece of insulating material designated as a whole by 4|,Which may be conveniently termed the fuse plug body. This body has an exteriorly tapered annular wall portion 42 within which there is a fuse chamber 43. Through the bottom of the fuse chamber there is a centrally located hole 44 and two circumferentially located holes 45. About the hole 44 there are four upstanding projections 46; and within the hole 44 there is a sheet metal clutch thimble 41 (Fig. 1) which is fixed to the body 4| by lower flange 48 and upper flange 49. To prevent relative rotation between the thimble 41 and the body 4|, the metal of the upper flange 49 is pressed down between the vertical projections 46 (Fig. 3) as shown in Fig. 1.

The lower part of the body 4| is formed into inner and outer depending skirt portions 58 and 5| which fit, respectively, inside and outside of annular projection 38 of the adapter body 2 On the exterior of body 4| there is an annular ledge 52 having three vertical projections 53; and from this shoulder six grooves 54 run down the outer face of skirt 5|.

A screw thimble 55 of sheet metal is telescoped over the body 4| and has an interrupted inwardly projecting flange 56 which lies on top of the annular ledge 52 and rotatively interlocks with the vertical projections 53. A fuse link 51 passes from the clutch thimble 41, through a notch 58 in the top of the body wall 42, down a vertical groove 59 on the exterior of wall 42, and beneath the flange 56 of screw thimble 55. This fuse link 51 may be soldered to the thimbles 41 and 55, as indicated at 41a and 55a.

Over the fuse body 4| there is telescoped a molded fuse cap 6|] of insulating material which has a depending skirt portion 6|, a roughened edge 62, and a central aperture 64. The cap 60 is preferably cemented to the fuse body 4|; and beads 4|, 4| and 66 may be used (optionally) to form a secure interlock with the cement. These beads may also be used (either with or without cement) to give a frictionfit between the body 4| and the cap 68, notwithstanding slight manufacturing variations in size. Where a friction fit is desired, the parts are so proportioned that in assembly the bead 66 (on the cap) clears the bead 4 la (on the fuse plug body) and then as the parts approach the relation shown in Fig. 1, the beads 4 la and 4| b firmly engage the cap skirt 6| and the bead 66 firmly engages the vertical beads 4| b, the beads yielding or scraping away to take care of manufacturing variations in fit. Cut-outs 63 (Fig. 6) in the bottom of the cap skirt 6|, engage projections 53 and rotativeiy interlock the fuse cap and the fuse body. Before the cap 68 is telescoped in place a window disc of glass or other suitable material such as mica is placed on top of the body 4| and is clamped in place by the cap 60.

It will be seen that the structure provides for easy assembly. In assembling the adapter 28, the spring 32 may be secured to plug 3| and then the plug may be inserted into the adapter body 2|. The outer end 33 of the spring may then be moved circumferentially to give the spring the desired tension and then be slipped into place in one of the slots 34. The cap 24 may be dropped into the bottom of sleeve 21; and then when the sleeve has been screwed onto the adapter body except for a fraction of a turn, the barb 35 may be inserted through the slot in the sleeve and the sleeve screwed home to hold the cap 24 and the barb 35 in place.

In assembling the fuse plug, the thimble 41 may be put in the body 4| and the fuse link 51 laid in place in the position shown in Fig. 1, being soldered at 41. Then the screw thimble 55 may be telescoped over the body 4| and the solder applied at55a'. Following this window 65 may be inserted and the cap 60 be forcibly telescoped into place on the body 4|, cement preferably being used between the cap and body.

In use the fuse plug is screwed into the adapter, and then the assembly of plug and adapter is screwed into the fuse socket l2. The plug may, of course, be readily removed, but the barb 35 engages the screw shell M of the socket, thereby preventing removal of the adapter by an unauthorized person. In the absence of a fuse plug, the circuit making and breaking plug 3| is held by spring 32 in an upward position where it is out of engagement with contact 25. Thus it will be difficult, if not impossible, for an unauthorized person tampering with the installation to bridge the circuit without inserting a fuse.

Each adapter 20 may be designed to receive fuses of not over a certain given rating, and this rating may be permanently marked on the top surface of wall 38. For example, an adapter designed to be fused with not over a 15 ampere fuse may have 15 amperes molded on top of the wall 38. The fuse plugs of graduated rating have graduated thicknesses of skirt 5|; and all fuse plugs which are of greater than 15 ampere capacity have the depending skirt portion 5| so thick that it will not telescope over the wall 30 of a 15 ampere adapter, thereby preventing their insertion in a socket containing a 15 ampere adapter. Fuses of lower rating have the skirt 5| thinner than fuses of higher rating, thereby permitting their insertion into sockets containing adapters of higher (but not lower) rating. For example, 5, 10, and 15 ampere fuses can be inserted into sockets containing a 15 ampere adapter, but fuses of 20, 25, etc. amperes cannot be.

When a replacement fuse is inserted it is simply screwed into place in the sleeve 21 of the adapter;

and the conical clutch end of thimble 41 engages I the conical end of circuit making plug 3| and screws it down to the position shown in Fig. 1 of the drawings, thus completing the circuit. When the fuse blows the gases generated may escape through holes 45 to grooves 29 and. out through grooves 54 and cut away areas 63.

As may be seen from Fig. 1 of the drawings, the thread which is rolled into the adapter sleeve 21 is of the same pitch as the thread in socket I4 and the thread of thimble 55, but is of greater depth from crown to root than either of these other threads. Thus the maximum external diameter of thimble 55 is less than the minimum internal diameter of socket I4 so that it will be impossible to insert the fuse into a socket not equipped with an adapter.

The vertical distances between the top of center contact I5 and both the bottom and top'of the fuse socket vary considerably in sockets made by different manufacturers. There are sockets 'of different depths and there are differences in the height of the center contact above the bottom of the socket. For example, in Fig. 1 there is shown a low lying center contact which has its top surface close to the bottom of the socket, while in Fig. 10 there is shown a relatively high center contact which has its top surface quite a distance above the bottom of the socket. These variations cause no difficulty in the construction or use of the present invention. In the forms shown in Figs. 1, l0 and 11 the adapter is screwed directly against the bottom contact and in all forms shown the fuse plug is screwed into the adapter and not into the original fuse socket.

In Fig. 1 circuit is made and broken between the adapter contact 25 and the plug 3|, so that constant circuit breaking clearance is assured (when a fuse is removed) regardless of the height of the center contact I5 above the bottom of the socket.

In the sockets made by the various manufacturers there is also considerable variation in the screw shells i4. Some have a deep shell threaded for its entire depth as shown in Fig. 1; others have only a shallow shell; and still others have a shell which presents only a thread or two that are spaced way above the bottom of the socket. Thesevariations also cause no difliculty with the plug and adapter of the present invention as they plug is not.dependent upon the screw threads of the main socket, and the'adapter has a long sleeve threaded throughout its entire length so that it can cooperate with socket threads either hear the bottom of the socket or near the top of the socket. y

The construction shown in' Fig. 10 is so generally similar to that which has previously been described that it will only be necessary to point out the major differences between it and the. construction of Fig.1. The outer end of spring II which rotatively biases the circuit making plug I2 is formed into a vertically extending spring loop I3, which is inserted into and frictionally grips any one of several circumferentially positioned holes I4. The clutch engagement between the plug I2 and the fuse is just the reverse of that shown in Fig. 1 in that themale clutch memher is carried by the fuse and the plug 'I2-is re being essential. A plug is biased upwardly by a helical spring 9|, but is adapted to be forced against lower contact 92 by direct thrust of a ,push member 93 carried by the fuse plug. The

end of the push member may have a nose that enters a recess in plug 90 for the purpose of breaking strips of tinfoil which may be placed. over the adapter in an attempt to-bridge a blown fuse. When the fuse plug is removed, the spring 9I retracts the circuit making plug- 90 from the position shown in dotted lines-to the position shown 'insolid'lines. In assembly, the plug .90 and spring 9| may be inserted in the adapter body, and then the end of plug 90 may be rivetted to a washer 94. The remainder of the assembly may follow that discussed in connection with Fig. 1, a barb being used if desired to prevent removal of the adapterfrom a socket.

The construction shown in Figs. 12. and 13 combines some of the features shown in the previous forms and presents certain different features. The construction of the fuse plug designated as a whole by I 00 is preferably the same as that described in connection with Fig. 1 except for the adapter actuating member I0 I. This member is a hollow stamped drawn sheet metal thimble which is inserted from the bottom and has its upper end eyeletted-or rivetted over and between projections such as 46 (Fig; 3). The circuit making plug I02 of the adapter is arranged similarly to the plug 90 of Fig. 11, but the washer I03 that is rivetted to it has lateral extension I04, I04 which slide in vertical grooves I05, I 05. Thus as a fuse is inserted, plug I02 cannot rotate while member IOI does. The relative rotation between IM and. I02- as a fuse is being inserted is exceedingly effective in tearing and-displacing strips of tinfoil which may be placed on top of the adapter in an attempt to bridge a blown fuse.

The screw thimble I06 is a tight screw fit with the adapter body i0! and, of course, a barb or the like may be used to retain the adapter in a socket. The'circuit making plug I02 is adapted to directly engage the bottom socket contact, but constant circuit breaking clearance (regardless of the height of the center contact) is :maintained, nevertheless. Aperture I08 is-made so small that it cannot receive the center contact of any of the various commercial fuse sockets. Thus, the. depth of insertion of the adapter into a socket is determined by top .of the socket center contact, and hence the circuit breaking clearance will always be the distance between the bottom of the adapter and the bottom of plug I02 when retracted. I

Of course, the invention may be embodied in various specific forms and the forms disclosed are merely illustrative, being the best forms in which I have contemplated applying the invention.

I claim:--

1. A fuse organization comprising: a receptacle for a fuse plug, said receptacle having a pair of contacts; an adapter within the receptacle, said adapter having a first contact engaging one of the receptacle contacts, and a movable second contact normally biased into non-engaging position with respect to said first contact; and a fuse plug cooperable with the adapter to move said second contact into engagement with said first contact.

2. A fuse organization comprising: a receptacle for a fuse plug, said receptacle having a pair of contacts; an adapter within the receptacle, said adapter having a first contact engaging one of the receptacle contacts, and a'movable second contact normally biased into non-engaging position with respect to said first contact; and a fuse plug cooperable with the adapter to move said second contact into engagement with said first contact; said adapter and plug being provided with interfitting formations which prevent the insertion of a fuse of undesired rating.

3. An electrical screw plug organization comprising: a socket having a sheet metal shell with screw threads pressed therein; an adapter having a sheet metal sleeve with screw threads pressed therein, said sleeve being screwed into said shell and the sleeve threads being of greater depth from crown to root than the shell threads; and a plug-like element screwed into said sleeve.

4. An electrical screw plug organization comprising: a socket having a sheet metal shell with screw threads pressed therein; an adapter having a sheet metal sleeve with screw threads pressed therein, said sleeve being screwed into said shell and the sleeve threads being of greater depth from crown to root than the shell threads; a plug-like element screwed into said sleeve; a circuit breaker within said adapter; and means carried by the plug to actuate said circuit breaker.

5. A circuit breaker for a cup-like electric socket having a bottom contact, comprising: a body insertable into the socket; a first contact carried by the body to engage said socket contact when the body is inserted; and a second contact carried by said body, said second contact being movable into and out of engagement with said first contact.

6. A circuit breaker for a cup-like electric socket having a bottom contact, comprising: a body insertable in the socket; a first contact carried by the body to engage said socket contact when the body is inserted; a movable second contact carried by said body; and a spring operable to bias said second contact into non-engaging position with respect to said first contact, said second contact being movable against pressure of the spring to engage said first contact.

7. A fuse organization comprising: a screw socket having a bottom contact; an adapter screwed into said socket, the adapter having a first contact engaging said socket contact and having a movable second contact normally spring biased into non-engaging position with respect to said first contact; and a fuse plug screwed into said adapter, the plug having means to advance said second contact into engagement with said' first contact.

8. A fuse organization comprising: a screw socket having a bottom contact; an adapter screwed into said socket, the adapter having a body portion carrying a first contact which engages said socket contact and having a second rotatable contact threaded to the body portion, the second contact being normally spring biased into non-engaging position with respect to said first contact; and a fuse plug screwed into said adapter, said plug having means operative to rotate said second contact and advance it into engagement with said first contact.

9. A fuse organization comprising: a screw socket having a bottom contact; an adapter screwed into said socket, the adapter having a body portion carrying a first contact which engages said socket contact and having a second reciprocatory contact, the second contact being normally spring biased into non-engaging position with respect to said first contact; and a fuse plug screwed into said adapter, said plug having means which pushes said second contact into engagement with said first contact.

10. A circuit breaker for a cup-like electric socket having a contact, comprising: a body insertable into the socket; a first contact carried by the body to engage said socket contact when the body is inserted; and a second contact carried by said body, said second contact being movable into and out of engagement with said first contact.

11. A fuse organization comprising: a screw socket having a bottom contact; a circuit break ing adapter to be screwed into said socket, the forward end of the adapter being shaped to engage the surface of said bottom contact to limit the insertion of the adapter in the socket, and the adapter having a movable contact normally biased into constant circuit breaking clearance with respect to said bottom contact; and a screw plug fuse cooperable with the adapter to advance said movable contact into engagement with said bottom contact.

12. A fuse organization comprising: a screw socket having a bottom contact; a circuit breaking adapter to be screwed into said socket, the depth of insertion of the adapter being determined by the top surface of said bottom contact, and the adapter having a reciprocatory contact normally biased into constant circuit breaking clearance with respect to said bottom contact; and a screw plug fuse having means to engage said reciprocatory contact and advance it into engagement with said bottom contact.

RALPH W. E. MOORE. 

